1. Field of the Invention
This invention relates to a scanning type image formation apparatus capable of selectively changing image magnifications.
2. Description of the Prior Art
To change an image magnification, it is necessary to change the length of the light path correspondingly to a selected magnification. To change the length of the light path, it is generally practised to change the position of a movable mirror for scanning an original. Scanning type image formation apparatuses provided with such a device for changing the length of the light path are described in U.S. Pat. Nos. 3,614,222; 3,884,574; 3,914,044 and 4,168,905 and Japanese Patent Publication No. 34731/1976. These patents disclose different light path length changing devices, but these devices are common in that the position of a portion of a wire for transmitting a drive force to the movable mirror for scanning an original is changed by magnification changing operation, whereby changing the position of the mirror.
A drive force for moving the mirror to scan the original is applied to the wire, but the known devices in which the position of a portion of the wire is changed to change the length of the light path, as described above, actually require a complicated mechanism for preventing said drive force from imparting an adverse effect to wire position changing means to cause an error in the length of the light path or for preventing the wire position changing means from acting on the drive force to cause fluctuation of the original scanning velocity. This has also precluded the compactness of the apparatuses.